1. Department of Photonics, National Sun Yat‐sen University, Kaohsiung 80424, Taiwan;2. Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan;3. Department of Photonics and Institute of Electro‐Optical Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan;4. Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan;5. Department of Physics, National Sun Yat‐sen University, Kaohsiung 80424, Taiwan
Abstract:
A tantalum pentoxide‐based (Ta2O5‐based) micro‐ring all‐optical modulator was fabricated. The refractive index inside the micro‐ring cavity was modified using the Kerr effect by injecting a pumped pulse. The transmittance of the ring resonator was controlled to achieve all‐optical modulation at the wavelength of the injected probe. When 12 GHz pulses with a peak power of 1.2 W were coupled in the ring cavity, the transmission spectrum of the Ta2O5 resonator was red‐shifted by 0.04 nm because of the Kerr effect. The relationship between the modulation depth and gap of the Ta2O5 directional coupler is discussed. An optimized gap of 1100 nm was obtained, and a maximum buildup factor of 11.7 with 84% modulation depth was achieved. The nonlinear refractive index of Ta2O5 at 1.55 μm was estimated as 3.4 × 10?14 cm2/W based on the Kerr effect, which is almost an order of magnitude higher than that of Si3N4. All results indicate that Ta2O5 has potential for use in nonlinear waveguide applications with modulation speeds as high as tens of GHz.
